1. Field of the Invention
The present invention relates to a cleaning processing system for performing a series of processing for applying a cleaning processing to a substrate such as a semiconductor wafer and to a cleaning processing apparatus for actually applying a cleaning processing to the substrate.
2. Description of the Related Art
In the manufacturing process of, for example, a semiconductor device, it is necessary to maintain a high cleanliness on the front and back surfaces of a semiconductor wafer, particularly, the surface of the wafer on which a semiconductor device is formed. For maintaining the required high cleanliness, the surface of the wafer is cleaned both before and after each of various manufacturing processes. Particularly, in the photolithography process, cleaning of the wafer surface is indispensable. For the cleaning of the wafer surface, it was customary to employ the scrub cleaning in which a rotating brush is reciprocated between the central portion and the peripheral portion of a rotating wafer while supplying a cleaning liquid onto the rotating wafer and while allowing the brush to abut against the wafer surface so as to remove the contaminant such as particles attached to the wafer surface.
The scrub cleaning is performed by using a cleaning processing system equipped with a plurality of process units including a plurality of scrub cleaning units for performing a series of processing. In the conventional cleaning processing system, a plurality of scrub cleaning units are generally arranged in a planar arrangement.
However, the diameter of the wafer has been increased in recent years. Where the scrub cleaning unit and other units arranged in the cleaning processing system such as a heating unit for applying, for example, a drying treatment to the wafer, an inverting unit for inverting the wafer so as to apply a scrub cleaning to the both surfaces of the wafer and the transfer mechanism of the wafer are enlarged in conformity with the enlargement of the wafer, the footprint of the cleaning processing system is markedly enlarged.
With enlargement of the footprint, it is rendered difficult to install the cleaning processing system in the existing clean room. Therefore, it is expected that the necessity may arise to expand the existing clean room or to newly install an additional clean room, leading to an increase in the facility cost. Such being the situation, it is of high importance to suppress as much as possible the increase in the footprint accompanying the enlargement of the wafer.
On the other hand, a problem remains unsolved in the conventional scrub cleaning unit that, for example, a mist of the cleaning liquid generated mainly around the brush is scattered so as to contaminate the cleaning process chamber. It is also possible for the scattered cleaning liquid to be attached to the mechanism for moving the brush, i.e., to the driving mechanism of the arm holding the brush, so as to bring about a defective operation. By contraries, it is also possible for the particles generated in, for example, the driving mechanism to be diffused within the cleaning apparatus, with the result that the diffused particles are attached to the wafer so as to degrade the wafer.
An additional problem to be noted is that, in the prior art, a single brush is mounted to a single scrub cleaning unit. In the cleaning processing using a single brush, the processing time per wafer is increased with increase in the diameter of the wafer so as to lower the through-put. It should also be noted that the miniaturization and the progress in the degree of the high density integration of the device formed on the substrate to be processed are being promoted simultaneously with the enlargement of the wafer. In this connection, the substrate is required to be subjected to a cleaning processing of a higher cleanliness. Where the cleaning processing with an improved cleanliness is applied to the wafer having a large diameter, a long time is required for the cleaning processing of a single substrate. It follows that it is required to develop a cleaning processing apparatus capable of performing a uniform cleaning processing in a short time over the entire substrate to be processed.